Printers and plotters used for generating text and graphics on cut sheets of printed media have previously been equipped with literally hundreds of different types of media accumulating apparatus. These apparatus are either an integral part of the printer or plotter or they are removably attached thereto and are normally readily accessible to an operator for retrieving the media having text or graphics printed thereon. In the field of plotters and particularly large format plotters which produce correspondingly large size sheets of printed media, a problem of sheet crumpling and curling is presented by the manner in which these sheets are transported and stacked after printing or plotting thereon.
In the past, many differently configured devices have been used for the collection of these cut sheets and have been variously referred to in these arts as "catch trays", "catch bins", "paper collection trays" and the like. However, none of these known passive prior art media collection devices have been operative to prevent a certain undesirable crumpling and curling of the cut sheets and stack and arrange the cut sheets in an orderly fashion. This fact has in part been a result of the specific configurations of these sheet collection devices and their corresponding media handling and operational characteristics. More particularly, this introduction of crumple and curl into the accumulated cut sheets has been a result of the environmental conditions (e.g. humidity) and winding tension to which the paper is subjected at the manufacturer, coupled with the inability of these paper and media handling devices to uniformly distribute the weight of the accumulated media during both media transport and stacking. This introduction of crumple and curl into the cut sheets has also been a result of the inability of these prior art paper stacking apparatus to adequately move cut sheets out of the way of the upstream moving paper, sometimes causing the paper to jam up in the plotter and be crushed. Additionally, when conventional paper trays are used to accumulate cut sheets being fed into the tray one after another and sliding on top of the previous sheet, the sheets may hit earlier received sheets unevenly at the edges when the latter become skewed in the tray. This can also aggravate the problem of sheet curling and buckling.
Other active types of paper collection devices such as reciprocating tables have been known to work quite well in certain applications and environments. However, these "active" devices require motors, control logic and related electronic circuitry and involve significantly higher costs relative to passive paper stacking devices of the type disclosed and claimed herein.